Messages in this thread | | | Date | Fri, 5 Apr 2013 01:41:29 +0200 | Subject | Re: sched/cputime: sig->prev_stime underflow | From | Frederic Weisbecker <> |
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2013/4/4 Dave Hansen <dave@sr71.net>: > With the 3.9-rcs (and probably much earlier) I'm seeing some weird top > output where the cpu time "spent" is millions of hours: > > 445 root 20 0 0 0 0 S 0 0.0 5124095h kworker/45:1 > 404 root 20 0 0 0 0 S 0 0.0 5124095h kworker/4:1 > > I see it mostly with kernel threads, but it doesn't seem to happen on my > distro kernel (3.5 era). The suspect code is in thread_group_times(): > > sig->prev_stime = max(sig->prev_stime, rtime - sig->prev_utime); > > In my case, I caught it with rtime=34 and sig->prev_utime=35. This code > _looks_ to be pretty mature, coming in at commit 0cf55e1e in 2009. The > system I'm running on _does_ have some non-sync'd TSCs, but they are at > least being detected, so I expect the fallout to be minimal: > > tsc: Marking TSC unstable due to check_tsc_sync_source failed > > config: > > http://sr71.net/~dave/linux/config-bigbox-04042013.txt > > The dumb fix here would seem to be to just check "rtime < > sig->prev_utime". Any thoughts?
Hi Dave,
Does this patch fix the issue for you? https://lkml.org/lkml/2013/4/4/112
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